Selective belt printing apparatus for printing a line at a time

ABSTRACT

Printing apparatus is provided in which an entire line of print is printed at one time and wherein a sheet of paper is advanced past a printing station so that a series of lines of printing can be successively printed thereon. The printing is effected in a plurality of parallel columns, with which are aligned a like number of belts on which are located the print characters. These belts are driven by one or more drums in repetitive cycles. In each cycle each of the belts is brought to a halt with the desired character at the printing line in the printing station and when a line of print has been thusly compiled, a single hammer unit drives the characters against a ribbon to print the line on the paper. The belts are then returned to an initial position of rest in preparation for the next succeeding cycle for the next succeeding line of print. The print hammer may be actuated from the same source of power which drives the drum or drums and there may be related to this source of power a stepping device which steps the paper through the printing station.

O United States Patent 1151 3,665,850

Berger et al. 1 May 30, 1972 s41 SELECTIVE BELT PRINTING 3,139,8187/1964 Koehn ..1o1 93 c APPARATUS FOR PRINTING A LINE AT 3,139,8227/1964 Lj g "W C A TIME 3,364,852 1/l968 Ragen ..lOl/93 C [72]Inventors: Ralph Berger, McLean, Va.; Howard Sat- PrimaryExaminer-William B. Penn terlee, Madeira Beach, Fla. Attorney-Roberts &Cohen [73] Assignee: New England Merchants National Bank, 57] ABSTRACTBoston, Mass. Printing apparatus is provided in which an entire line ofprint [22] Filed 1969 is printed at one time and wherein a sheet ofpaper is advanced [21] Appl. No.: 852,697 past a printing station sothat a series of lines of printing can be successively printed thereon.The printing is effected in a plurality of parallel columns, with whichare aligned a like 2% number of belts on which are located the printcharacters. '6 l l l These belts are driven by one or more drums inrepetitive cy- 1 o cles. In each cycle each of the belts is brought to ahalt with the desired character at the rintin line in the rintin stationh p g h l p 1 d g l and w en a line of print has been t us y compi e asing e [56] Reta-mm cued hammer unit drives the characters against aribbon to print the UNITED STATES PATENTS line on the paper. The beltsare then returned to an initial posinon of rest 1n preparanon for thenext succeedmg cycle for the MlleS 1 1 next succeeding line of print Theprint hammer may be actu- 2'168-364 8/ 1939' Schaefer 101/336 X atedfrom the same source of power which drives the drum or 2'2o4153 6/1940 yet 101/111 X drums and there may be related to this source of power a 2.1 3/ 1945 Keuper 101/ 1 1 1 X stepping device which steps the paperthrough the printing sta- 2,90l,540 8/1959 Canepa.... 101/111 X fi3,010,387 11/1961 Deutsch... l01/1llX 3,135,195 6/1964 13 Claims, 15Drawing Figures Potter 101/93 C S0! A/0 ID ELECTRON/C 56H P067770CONTROL 66 Mao/64rd? 85 if)? RALPH BERGER HOWARD sATTERLEE A'I'TORMCYSPatented May 30, 1972 I 6 Sheets-Sheet 2 EJTZL u g l .II.II.IL.LNLFLrLr.

I mun 1 mu llHl [Trim NHL RALPH QERQER HOWARD SAT-TERLEE Patented May30, 19'?2 6 Sheets-Sheet 5 QR Q mwm mm E S E R L O R H RE N T EMT EM meD M P W A0 RH \mm Patented May 30, 1972 3,665,850

6 Sheets-Sheet L RALPH BERGER HOWARD SATTERLEE I i Y Patentd May 30,19123,665,850

6 Sheets-Sheet 5 INVI'JNIOHS RALPH BERGER HOWARD SATTERLEE Patented May30, 1912 3,665,850

6 Sheets-Sheet 6 SELECTIVE BELT PRINTING APPARATUS FOR PRINTING A LINEAT A TIME DRAWING FIG. 1 is a diagrammatic side view of a printingapparatus provided in accordance with one embodiment of the inventionemploying a plurality of driving drums;

FIG. 2a is a front view, on enlarged scale, of one of the driving drums;

FIG. 2b is an enlarged view of a portion of the aforesaid driving drumillustrating in cross-section printing belts supported on the said drum;

FIG. 3a is a side view of a printing belt employed in the invention instretched-out condition;

FIG. 3b is a top view of the belt of FIG. 3a;

FIG. 4a is a diagrammatic illustration of the alignment of a pluralityof belts when a printing operation is ready to be effected;

FIG. 4b is a diagrammatic view of the belts of FIG. 4a in theiralignment at the start of a printing cycle;

FIG. 5 is a detailed view on enlarged scale illustrating how the ends ofthe belts are connected together in an endless loop;

FIG. 6 is a diagrammatic view on enlarged scale showing further detailsof the apparatus of FIG. 1 relative to the supply of paper;

FIG. 7 is a diagrammatic view illustrating the printing ribbon supplyfor the apparatus of FIG. 1;

FIG. 8 is a diagrammatic view of a clock or position indicator for usein the apparatus of FIG. 1;

FIG. 9 illustrates in diagrammatic form a modification applicable to theapparatus of FIG. 1;

FIG. 10 diagrammatically illustrates a second embodiment of theinvention; and

FIGS. 11a and 11b diagrammatically illustrate the printing elements andarrangement for the apparatus of FIG. 10.

FIELD OF INVENTION This invention relates generally to printingapparatus and more particularly to a medium speed printer capable ofprinting, by way of example, 60 to 100 lines per minute.

It is an object of the invention to provide an improved printingapparatus of the aforenoted type capable of reliably printing by the useof components which are readily and economically assembled and serviced.

SUMMARY OF INVENTION In accordance with the invention there is provideda printing apparatus which comprises a sheet supply means for displacinga sheet of record medium such as paper through a printing station in adeterminable direction to enable line-byline printing on said sheet inlines perpendicular to said direction and in a multitude of parallelcolumns aligned with said direction. .A plurality of belts is employedwith the belts being arranged in parallel to the aforesaid columns towhich they correspond in number and in alignment. These belts preferablyinclude like assortments of print characters serially distributed alongcorresponding lengths thereof.

The belts are driven by suitable driving means such that the aforesaidlengths are driven at least partly through the aforesaid printingstation. A locating means is operatively associated with each of saidbelts to terminate movement thereof through the station so that apreselected print character is brought to a printing line at theprinting station in each of the said columns.

in accordance with the invention a printing means is employed whichdisplaces the thusly compiled line of print characters towards the sheetsimultaneously to print an entire line at one time.

In further accordance with the invention, the means for driving thelengths bearing the characters through the printing station includesmeans for returning such lengths to a starting position from which thelengths can be driven in entirety through the printing station in asucceeding cycle.

To provide for succeeding cycles there is provided apparatus forstepping the sheet line-by-line through the printing station in equaltime increments. Also provided is a device to supply print ribbonbetween the sheet and print means.

As will be shown in greater detail hereinafter, the drive means andprint means cooperatively include at least one drum for releasablydriving the belts and a print hammer extending linearly across theaforesaid columns at the printing station. Cyclical means is provided todrive the aforesaid drums cyclically and there are actuating meansresponsive to this cyclical means to actuate the print hammer.

According to one feature of the invention, the cyclical means includes apinion driven by a rack and in turn driving a sprocket which drives achain which in turn drives a second sprocket coupled to the drum ordrums driving the aforesaid belts. A crank is employed for driving theaforesaid rack and a cam is connected to and moves with the crank shaftand operates a toggle coupled to the print hammer.

Each of said belts may include two axially arranged sections, one ofwhich includes the print characters and the other of which includesratchet teeth by means of which the belts may be engaged for beinghalted with a proper character in position. This halting operation maybe effected, for example, by a sole operating stop which selectivelyengages one of the aforesaid teeth.

The sheet supply device employed in accordance with the invention maypreferably include a ratchet and pawl assembly to supply driving powerto a sprocket drive, the pawl being connected to the print hammerthrough intervening mechanisms so that the operation of these twoelements is synchronized.

In accordance with one embodiment of the invention, the belts are drivenby a plurality of drums with spaced parallel axes.

In accordance with another embodiment of the invention, a single drum isemployed which is encircled by the aforesaid belts.

BACKGROUND There are a number of printer constructions which employdisplaceable belts cooperating with print hammers to effect a printingoperation.

One such apparatus is known from U.S. Pat. No. 3,113,509 (V. R. Simpson)which issued Dec. 14, 1963. As will be seen from the description whichfollows hereinafter, the Simpson apparatus is distinguishable in that itemploys a belt arrangement wherein the belt is aligned with the printedline and because it further employs a print hammer arrangement which isunlike that employed in accordance with the present invention.

U.S. Pat. No. 3,164,084 (W. G. Paige), which issued Jan. 5, I965,likewise employs a plurality of belts to constitute a high speed beltprinter, there being moreover employed an internal hammer arrangement.The apparatus disclosed by this patent is unlike that of the presentinvention in that it employs a plurality of print hammers and does notprovide for bringing a multitude of characters to a single line of printto be operated upon simultaneously by a single hammer.

U.S. Pat. No. 3,188,947 (W. G. Paige), which issued June 15, I965,similarly provides a plurality of belts, but is distinguishable in thata plurality of print hammers is employed, each of which is associatedwith a relatively small number of belts. There is not shown in thispatent an arrangement whereby an entire line of print is effectedthrough the use of a single print hammer and consequently thearrangement of this patent is considerably more expensive andcomplicated than the arrangement of the present invention.

DETAILED DESCRIPTION An exemplary purpose of the present invention is toprovide a medium speed printer capable of printing for example, 60 tolines per minute. In a preferred machine each line consists of, forexample, I32 columns wherein the characters are spaced one-tenth of aninch apart. The characters, by way of example, occupy an area 0.093 X0.063 inch in size.

In the particular machine under discussion, there are six lines of printper inch. Each row or line of 132 columns is set up during a singlecycle and at the end of the cycle the entire row or line of charactersis printed at one time.

At the end of a given portion of a printing cycle and directly after theprinting of a single line, the sheet of paper on which printing is beingeffected advances and provision may be made that the associated printingmachine will advance at the same time.

The cycle then includes a reverse portion causing all columns to bereset to zero or starting position. As will be seen hereinafter, theterm reverse is a generalized expression since the cycle can be zeroizedby circular movement all in the same direction.

A printing operation consists of a plurality of repeated cycles in eachof which a line of print is first assembled and then employed in asingle hammer operation.

With reference to the details schematically shown in FIG. 1, a printingapparatus in accordance with one embodiment of the invention comprises aplurality of drums 20, 22, 24, and 26 rotatable on shafts 28, 30, 32,and 34, the drums and shafts having spaced and parallel axes arranged atthe four comers of a rectangle.

A plurality of belts, such as diagrammatically indicated at 38,encircles the aforesaid drums and are driven by these drums in a mannerwhich will be indicated with greater particularity hereinafter.

On each of the above mentioned shafts is mounted a sprocket wheel. Moreparticularly, on shaft 28 is mounted a sprocket wheel 40, there beingadditionally provided sprocket wheels 42, 44, and 46 mounted on shafts30, '32, and 34 respectively.

The aforesaid sprocket wheels are engaged and driven by a chain 48arranged as an endless loop and in turn engaged by and driven by asprocket wheel 50. Rotation of the sprocket wheel 50 drives the chain 48thereby driving sprocket wheels 40, 42, 44, and 46, which in turn drivethe drums 20, 22, 24, and 26 and thereby the belts 38.

From FIGS. 2a and 2b can be seen the construction of the above noteddrums and the accommodation of the belts 38 thereon. Drum 20 isillustrated by way of example in FIG. 2a. It is a one-piece cylindricalelement provided with a plurality of annular grooves 52 separated byannular ribs 54. The drum may be, for example, two inches in diameterand the grooves 52 therein may be, for example, a total of 132 innumber, the grooves being spaced by the ribs 54 at a distance, forexample, of 0.100 inch. The drums may be made of any metal havingsuitable strength.

In FIG. 2a it is seen that the grooves 52 accommodate the belts 38 whichlie flatly against the drum in said grooves. By way of example, in FIG.2b are shown in section belts 38a, 38b, and 380. These belts are, by wayof example, 0.080 inch wide and 0.005 inch thick. They can be fabricatedof metal or plastic and can be coined, etched, or molded. The belts havesuch relationship with the drum that they are normally driven by thedrum when the drum is rotated. However, movement of the belts can bearrested without impeding movement of the drum.

The construction of the aforesaid belts is indicated with greaterparticularity in FIGS. 3a and 3b. Therein it can be seen that each suchbelt is formed of serially connected sections such as indicated bybrackets 56 and 58. Section 56 is the print character including section.In this section will be included a plurality of characters 60 which mayinclude, for example, the complete alphabet in capital letters, thecomplete alphabet in small letters, a series of numbers and whateverother signs and symbols are required to effect a normal printingoperation. In the preferred embodiment of the invention, 128 suchcharacters are provided.

The belt section 58 includes a plurality of ratchet teeth 62. As will beshown, the ratchet teeth constitute a part of the arrangement by whichthe belts are brought to a halt for the appropriate positioning of theaforesaid characters. For this reason the ratchet teeth are identical innumber to the number of characters 60. The pitch of the teeth andcharacters may, for example, be 0.166 inch and with 128 teeth andcharacters a total belt length of 42.6 inch will be involved.

FIGS. 4a and 4b show diagrammatically the use of belts of the aforesaidconstruction, it appearing that the belts 38 will be effectivelystaggered relative to each other to bring selected characters thereon toa print zone or area 64 for a printing operation. FIG. 4b shows that inthe beginning of a printing cycle the belts 38, or more particularly,the character 7 sections 56 thereon, are all in an initial startingposition of alignment with one another wherefrom the belts aretransported such that the sections 56 tend to move in entirety throughthe printing zone 64. In fact, and as will be shown in greater detailhereinafter, movement of the belts or belt sections is intercepted sothat these sections end up in the staggered relationship appearing inFIG. 4a for purposes of a printing operation. The staggered relationshipwill, of course, be different for different printing cycles and printingoperations so that a different line of print will be employed for eachprinting operation.

The belts are not employed in the stretched-out condition appearing inFIGS. 3 and 4. They are instead employed with their ends connected toform an endless loop. This appears in greater detail in FIG. 5 where canbe seen a spring-like serpentine element 66 formed, for example, ofberyllium copper or stainless steel, or the like, and connected to theends 68 and 70 of a belt 38.

Where the belt 38 is fabricated of metal, the element 66 will be welded,braized or soldered to the ends thereof which are to be connected. Ifthe belt 38 is fabricated of plastic, the element 66 can be molded intoposition.

In any event, and with reference once again to FIG. 1, the belts 38 aresupported in juxtaposed and parallel position corresponding to thecolumns which are to be printed and they are driven to move thecharacters past the printing zone by means of the aforenoted sprocket50.

Sprocket wheel 50 is mounted on shaft 72, having mounted thereon apinion gear 74. Pinion gear 74 is engaged and driven by a rack 76, rack76 in turn being driven by crank 78.

The crank 78 in the illustrated embodiment of the invention underdiscussion is driven continuously in one direction so that the rack 76is driven in opposite directions illustrated by arrow 80. This operatesto drive the belts 38 first in one direction and then in the otherdirection for each complete cycIe. It will be understood that, sincecrank 78 has a circular movement and rack 76 a linear movement, thespeed of the rack and thus the belts will be essentially sinusoidal, thebelts coming gradually to a zero velocity at which printing may beeffected. The magnitude of movement which the belts 38 undertake is suchthat due to such movement all of the characters on each belt will beable to move past the printing station.

In fact, and as has been noted hereinabove, this movement is interceptedso that a preselected character on each belt will be arrested in saidprinting station. The mechanism for accomplishing this is illustrated inthe form of a solenoid 82 having associated therewith a stop 84. Thereis one such solenoid and stop for each belt and it is the function ofeach stop to engage one of the ratchet teeth on the associated belt ashas been described hereinabove. The time at which the stop 84 will moveinto a position of interference is controlled by an electronic control86, the details of which are not important to an understanding of thisinvention. However, it is to be understood that the electronic control86 operates in conjunction with a belt position indicator 88 which may,for example, be controlled by an element mounted on the shaft 72 so thatthe electronic control 86 may select. the character to be brought to theprinting station for a particular belt 38 depending on the data suppliedto the control 86 for purposes of controlling the printing operation.

The printing zone referred to hereinabove is a zone extendingtransversely of the columns of print and the direction of movement ofthe belts 38 and is, moreover, a zone which lies adjacent the print baror hammer 90 and the print back up bar 92 between which elements passall of the belts 38. There is also provided a print ribbon 94 by meansof which ink is deposited upon the record medium or sheet 96 of paperupon which the printing operation is to be effected.

Print hammer 90 is displaced by means of a toggle 98 including links 100and 102. When these links are in rectilinear alignment, hammer 90 isdisplaced towards back up bar 92 and a printing operation is effected.When links 100 and 102 are angularly related as in the illustratedposition thereof, the hammer 90 is withdrawn from the bar 92.

The relative attitude of links 100 and 102 is controlled by a linkage104 pivotally connected at 106 to a link 108 supported on a pin 110.This linkage system is controlled by a cam 112 mounted for rotation withcrank 78 on a shaft 1 14.

It will be appreciated from what has been stated hereinabove thatrotation of crank 78 drives rack 76 and creates the driving force forthe belts 38. It will now be ap preciated further that such rotationactuates the link 104 and the toggle 98 and thus the print hammer 90. Asa consequence thereof movement of the belts 38 and that of the hammer 90are related. They are more particularly related so that movement of thehammer 90 follows the least possible time in which a different charactercan be moved through the printing zone so that a complete selection ofcharacters is possible before the printing operation is effected.Specifically, this means that all of the characters on each of the belts38 will have the opportunity if not previously intercepted to move to aposition adjacent hammer 90 before this hammer will be motivated toeffect a printing operation.

The hammer 90 is mounted on lever 114, in turn pivoted on pin 1 16. Thisis employed in the control of paper supply as will soon be seen. As partof the paper supply apparatus there are provided sprockets 118 and 120coupled to a chain 122. Also there are provided guides 124 and 126. Thepaper 96 in strip or sheet form passes between the guides and theaforesaid chain and is engaged by the sprockets 118 and 120 and driventhrough the printing zone around the back up bar 92 and thence in thedirection of discharge as indicated by arrow 128. The drive of the paper96 is incremental and can best be appreciated from an examination ofFIG. 6.

In FIG. 6 is shown the back up bar 92 in association with the printhammer 90 and ribbon 94, the hammer being mounted as aforesaid on thelever 114.

An arm 130 contacts lever 114 and atop the arm 130 is pivotally mounteda pawl 132 supported on pin 134 and connected with arm 136. Pawl 132engages a ratchet wheel 138 connected with sprocket 118 such thatrotation of the ratchet wheel 138 rotates sprocket wheel 118 which iseffective through chain 122 to drive sprocket wheel 120. It will also beseen that the pawl 132 is loaded by spring 140.

From what has been stated hereinabove, it will now be appreciated thatmovement of the hammer 90 in upward direction against back up bar 92will carry arm 130 therealong and thus will carry along therewith pawl132.

Upward movement of pawl 132 will be to the extent of one tooth onratchet wheel 138 so that return movement of hammer 90 will cause pawl132 to displace ratchet wheel 138 by an amount which is equal to onetooth, this in turn corresponding to the distance equal to that betweensuccessive lines of print on the sheet 96. As aforesaid, when there aresix lines of print to the inch, this distance will be equal to 0.166inch.

Also to be noted in FIG. 6 is the solenoid 142 actuated by coil 144 forthe displacing of armature 146. Armature 146 cooperates with arm 136 todeactivate pawl 132 when it is desired that movement of the print hammer90 not be accompanied by corresponding movement of the paper driven bysprockets 118 and 120.

The drive of the ribbon 94 appears more particularly in FIG. 7, whereinit is seen that the supply of the ribbon 94 includes a supply spool 148and takeup spool 150. The paper is indicated again at 96 and theprinting zone at 64. It is to be understood that the ribbon ispurposefully passed at an angle relative to zone 64, since thereby awider ribbon can be employed which is easier to control than a narrowribbon. Movement of the ribbon 94 is provided by increment drive of atype corresponding to that employed for driving the paper.

FIG. 8 illustrates a clock or counter or position indicator 152 whichcan be mounted on the shaft 72 as aforesaid to provide information forthe belt position indicator 88 of FIG. 1. The element 152 may be asprocket wheel, a photoelectric device, a magnetic device or any othersuch device capable of generating pulses indicating movement of thewheel through the increments 154 corresponding to the various charactersto be printed.

One such wheel may be associated with sprocket drive 50 to indicate theoverall displacement which the drive tends to give to the belts 38.Pulses or other such signals derived from the element 152 will becounted in well known digital manner in the indicator 88 and this countwill be compared in the control 86 also in well known manner withdigital representations of the characters which are to be printed.Comparison when determined will be used to actuate the stops 84 to bringthe corresponding belts to a halt. This terminating of the motion of thebelts is possible due to the fact that the engagement between thesebelts and the associated drums is frictional and any given belt can bebrought to a halt with a selected character thereon in position at theprinting zone even though the remaining belts may still be movingthrough the printing zone.

In a given cycle when the time has elapsed for all characters to havebeen brought through the printing zone, as determined by the cycle ofcrank 78, hammer will effect a printing operation and the belts 38 willbe brought back to their initial position as determined by a stop (notshown) installed on each of the belts. The apparatus will then be readyfor the next successive cycle which will be a repetition of what hasbeen described above.

FIG. 9 illustrates a modification of which the apparatus of FIG. 1 issusceptible. This modification involves simply the adjustable mountingof the drums 24 and 26 on adjustable bearing supports 156 and 158. Thepurpose of this adjustment is to provide for taking up slack in thebelts 38 and also to align the characters to the print slot. Thisadjustment may require a take up of slack in the chain 48. Suchrequirement is met by the provision of a take up spool 160 mounted on aswingable arm 162.

A second embodiment of the invention appears in FIGS. 10 and 11, whereinit is seen that a single drum 164 can be employed instead of theplurality of drums descussed hereinabove. In this embodiment, belts 166encircle the periphery of the drum and are selectively brought to a haltby means of a pivotal element 168 mounted for pivotal movement on pin170 and controlled by solenoid 172. Movement of the paper 174 isdiagrammatically illustrated as being controlled by drives 176 and 178,the paper moving around a back up 180 for the printing of successivelines.

FIGS. 11a and 11b diagrammatically illustrate how printing is effected,the back up 180 in this case being displaced by links 182, 184, and 186to displace the back up toward and away from the drum and the print beltthereon in a manner generally like that which has been notedhereinabove.

What is claimed is:

1. Printing apparatus comprising sheet supply means for displacing asheet of record medium through a printing station in a determinabledirection to enable a line-by-line printing on said sheet in linesperpendicular to said direction and in a multitude of parallel columnsaligned with said direction, a plurality of belts parallel to saidcolumns and corresponding in number thereto, said belts including likeassortments of print characters serially distributed along correspondinglengths of said belts and having an initial position from which thebelts can be displaced, drive means for driving each of said lengthsthrough said station, said drive means being reversibly displaceable ata sinusoidally variable speed between two limits, locating meansselectively operable to engage with each of said belts to terminatemovement thereof through said station while said drive means continuesits movement in one direction toward one of said limits whereby apreselected print character is brought to a printing line at saidstation in each of said columns, and print means to displace the thuslycompiled line of print characters towards said sheet simultaneously toprint an entire line all at one time when said drive means is at one ofsaid limits, said locating means being operatively associated in timedrelation to the operation of said drive to be disengaged from said beltsto permit said belts to be returned by said drive means to said initialposition when said drive means is displaced in the other directiontowards the other of said limits.

2. Apparatus as claimed in claim 1, wherein the means for driving saidlengths through said station includes means for returning said lengthsto a starting position from which the lengths can be driven in entiretythrough said station in a succeeding cycle.

3. Apparatus as claimed in claim 1 comprising means to supply a printribbon between said sheet and print means and wherein said sheet supplymeans includes means for stepping the sheet line-by-line through saidstation in equal time increments.

4. Apparatus as claimed in claim 1, wherein said drive means and printmeans cooperatively include at least one drum for releasably drivingsaid belts, a print hammer extending linearly across said columns atsaid station, cyclical means to drive said drum cyclically, andactuating means responsive to the last said means to actuate saidhammer.

5. Apparatus as claimed in claim 4, wherein said cyclical means includesa pinion, a rack displaceable in opposite directions to drive saidpinion in alternate directions, a

sprocket coupled to said pinion, a chain driven by said sprocket, asecond sprocket coupling said chain to said drum, and a gear for drivingsaid rack alternately in opposite directions; and wherein said actuatingmeans includes a cam coupled to and moving with said gear and a togglecoupled to said hammer and actuated by said cam.

6. Apparatus as claimed in claim 1, wherein each said belt includes twoserially arranged sections one of which includes said print charactersand the other of which includes ratchet teeth.

7. Apparatus as claimed in claim 6, wherein said locating means includesa solenoid-operated stop for selectively engaging said teeth.

8. Apparatus as claimed in claim 6, wherein each said belt includes aspring element closing the belt in an endless loop.

9. Apparatus as claimed in claim 1, wherein the sheet supply meansincludes a sprocket drive, a ratchet and paw] assembly for driving thesprocket drive, said pawl being coupled to and driven by said printmeans, said print means having idle and active positions and drivingsaid pawl upon returning from active to idle position, and means forselectively preventing engagement of the pawl with said ratchet.

10. Apparatus as claimed in claim 1, wherein said drive means includes aplurality of drums, with spaced parallel axes, for frictionally engagingand driving said belts.

11. Apparatus as claimed in claim 10, wherein at least one of said drumsis adjustable, said drive means further including a chain for drivingthe drums simultaneously and means to take up slack in the chain toaccount for adjustment of said one drum.

12. Apparatus as claimed in claim 1, wherein said drive means includes asingle drum, said belts being arranged to encircle said drum.

13. Apparatus as claimed in claim 3, wherein the means to supply a printribbon includes means to supply the same at an angle across the printinglin

1. Printing apparatus comprising sheet supply means for displacing asheet of record medium through a printing station in a determinabledirection to enable a line-by-line printing on said sheet in linesperpendicular to said direction and in a multitude of parallel columnsaligned with said direction, a plurality of belts parallel to saidcolumns and corresponding in number thereto, said belts including likeassortments of print characters serially distributed along correspondinglengths of said belts and having an initial position from which thebelts can be displaced, drive means for driving each of said lengthsthrough said station, said drive means being reversibly displaceable ata sinusoidally variable speed between two limits, locating meansselectively operable to engage with each of said belts to terminatemovement thereof through said station while said drive means continuesits movement in one direction toward one of said limits whereby apreselected print character is brought to a printing line at saidstation in each of said columns, and print means to displace the thuslycompiled line of print characters towards said sheet simultaneously toprint an entire line all at one time when said drive means is at one ofsaid limits, said locating means being operatively associated in timedrelation to the operation of said drive to be disengaged from said beltsto permit said belts to be returned by said drive means to said initialposition when said drive means is displaced in the other directiontowards the other of said limits.
 2. Apparatus as claimed in claim 1,wherein the means for driving said lengths through said station includesmeans for returning said lengths to a starting position from which thelengths can be driven in entirety through said station in a succeedingcycle.
 3. Apparatus as claimed in claim 1 comprising means to supply aprint ribbon between said sheet and print means and wherein said sheetsupply means includes means for stepping the sheet line-by-line throughsaid station in equal time increments.
 4. Apparatus as claimed in claim1, wherein said drive means and print means cooperatively include atleast one drum for releasably driving said belts, a print hammerextending linearly across said columns at said station, cyclical meansto drive said drum cyclically, and actuating means responsive to thelast said means to actuate said hammer.
 5. Apparatus as claimed in claim4, wherein said cyclical means includes a pinion, a rack displaceable inopposite directions to drive said pinion in alternate directions, asprocket coupled to said pinion, a chain driven by said sprocket, asecond sprocket coupling said chain to said drum, and a gear for drivingsaid rack alternately in opposite directions; and wherein said actuatingmeans includes a cam coupled to and moving with said gear and a togglecoupled to said hammer and actuated by said cam.
 6. Apparatus as claimedin claim 1, wherein each said belt includes two serially arrangedsections one of which includes said print characters and the other ofwhich includes ratchet teeth.
 7. Apparatus as claimed in claim 6,wherein said locating means includes a solenoid-operated stop forselectively engaging said teeth.
 8. Apparatus as claimed in claim 6,wherein each said belt includes a spring element closing the belt in anendless loop.
 9. Apparatus as claimed in claim 1, wherein the sheetsupply means includes a sprocket drive, a ratchet and pawl assembly fordriving the sprocket drive, said pawl being coupled to and driven bysaid print means, said print means having idle and active positions anddriving said pawl upon returning from active to idle position, and meansfor selectively preventing engagement of the pawl with said ratchet. 10.Apparatus as claimed in claim 1, wherein said drive means includes aplurality of drums, with spaced parallel axes, for frictionally engagingand driving said belts.
 11. Apparatus as claimed in claim 10, wherein atleast one of said drums is adjustable, said drive means furtherincluding a chain for driving the drums simultaneously and means to takeup slack in the chain to account for adjustment of said one drum. 12.Apparatus as claimed in claim 1, wherein said drive means includes asingle drum, said belts being arranged to encircle said drum. 13.Apparatus as claimed in claim 3, wherein the means to supply a printribbon includes means to supply the same at an angle across the printingline.